In her letter, Monroe said she was losing the will to live, "My will is weak but I can't stand anything. I sound crazy but I think I'm going crazy. It's just that I get before a camera and my concentration and everything I'm trying to learn leaves me. Then I feel like I'm not existing in the human race at all."

The letter was handwritten and undated. The late iconic actress, who died from a drug overdose in August, 1962, apparently penned her note of despair on Hotel Bel-Air letterhead stationery. It's expected to fetch between $30,000 and $50,00 at the upcoming auction.

As for Lennon's letter, it reflects the deep tension between the late musician and bandmate McCartney. "Do you really think most of today's art came about because of The Beatles? I don't believe you're that insane - Paul - do you believe that? When you stop believing it you might wake up!" he wrote.

It was actually a two-page draft letter that was typed on a letterhead stationary with a picture of Lennon and his wife Yoko Ono within a circle with their lips almost touching. Containing lots of corrections, the undated and unsigned note is expected to sell around $40,000 to $60,000.

The letters are sold by an anonymous American collector. Among the items are Dwight D. Eisenhower's handwritten letters during World War II about news of the war and his devotion to his wife Mamie, and two big photo albums exchanged by Adolf Hitler and Benito Mussolini before the war erupted.

Selected items are set to be exhibited April 8-16 at Douglas Elliman's Madison Avenue art gallery before going under the hammer at the upcoming Profiles in History sale on May 30.